The present invention relates to a bone marrow biopsy needle, and more particularly to a bone marrow biopsy needle having an improved mechanism for gripping and withdrawing a biopsy core from the body of the patient.
U.S. Ser. No. 07/863,457 discloses in FIGS. 5A-5E a bone marrow biopsy needle including an outer tube with an inwardly tapered distal end, and an inner tube with a pair of opposed blades hinged to the inner tube at its distal end. The inner tube is slidable axially within the outer tube. The taper at the distal end of the outer tube defines a dead space radially outward of the needle opening. The blades have an open position in which they are contained within the dead space.
The outer tube is inserted into the bone being biopsied with the blades retracted into the dead space so as not to obstruct the entry of the biopsy into the space within the outer and inner tubes. The outer tube is sharp, as is customary, so as to enter the bone easily. Then, when the biopsy has entered the needle, the inner tube is pressed axially in the distal direction. The blades engage the tapered end of the outer tube, which folds them radially inward on their hinges, simultaneously cutting off the biopsy core and retaining it in the needle. A detent and blocking arrangement is provided for holding the inner and outer tubes in various relative positions.
Although the above-described needle is effective and greatly improves the ease and security of the bone marrow biopsy process, it would be desirable to make further improvements by reducing the number of moving parts and assembly steps required to manufacture the needle. More particularly, it would be desirable to simplify the hinge arrangement, as well as the detent and blocking arrangement.